Vagaries of the lavage white blood cell count in evaluating abdominal stab wounds

Abstract

The clinical value of an elevated white blood cell (WBC) count on a diagnostic peritoneal lavage (DPL) performed in an asymptomatic patient with a penetrating abdominal stab wound is controversial. We performed a comprehensive analysis of asymptomatic patients (no signs of peritonitis) with stab wounds who underwent an exploratory laparotomy based solely on a WBC count > 500/mm3 in the effluent of an open DPL. Twenty-eight patients, 25 with injury to the gastrointestinal (GI) tract and 3 with injury to the liver, obtained true-positive results from DPL. Their mean WBC count in lavage effluent obtained at a mean of 7.6 hours after the stab wound was 3,380/mm3 and their mean serum WBC count, obtained at the same time, was 12,324/mm3. Fifteen patients had false-positive results from DPL. They were lavaged at a mean of 7.2 hours after the stab wound, and had a mean lavage WBC count of 1,228/mm3 and a mean serum WBC count of 9,084/mm3. Patients lavaged at a mean 6 to 7 hours after an abdominal stab wound will have a significant incidence of false-positive studies based on an elevated WBC count alone. Lavage WBC counts > 3,000/mm3, particularly when associated with a serum WBC count > 11,000, are likely to be true positives and to indicate injury to the GI tract.